Description
Non-string fields need to support ignore_malformed when synthetic source is enabled. The idea is to store the field value "as-is" in its json representation and later use the the value reading it from a hidden stored field.
Here the strategy to adopt is similar to what we did for the ip type. We catch an exception happing when parsing the field value and if storing the malformed value is enabled we just use IgnoreMalformedStoredValues#storedField to store the value.
(Maybe we can do a nice refactoring before and avoid relying on catching the exception)